Most go the other way around. Start some plants. Take a clone from each, mark or number to know whitch mother it came from. Put them in 12/12 light and wait 2 to 3 weeks or untill they show sex. Any that are male kill it and the mother. If you have females then clone the hell out of the mother and your all females no guessing. This is the way I go. No males make it to the flower room.